High-frequency electrical apparatus



Sept 20, 1949. R. N. HALL ETAL HIGH-FREQUENCY ELECTRICAL APPARATUS Filed May l2, 1945 mh, m y. www w m n t ri t e. r a WJ t e@ mmwfA my .w. N wm .WJ .M m d A F operates.

Patented Sept. 20, 1949 UNITED :STATES PATE-Nr omer HIGH-FREQUENCY `fEIEC'-IRICAL APPARATUS Robert N. Hall, .Amandus H. .Sharbaugh, .and Lewi Tonks, Schenectady, N. Y., assignors to -Gen- '.eralElectric Company, a corporationoi.'.Newl

V"York Application May 12, 1945,;se`ria1No-s9a4914 i 11 claims. (olfato-#215) Our invention relates lto Vhigh Vfrequency apparatus and particularly .to in'lproved arrangements for controlling .the `coupling .betweena resonant .structure .and an .output circuit. While not `limited thereto, .our invention `.is particularly well adapted .for .controlling .the .coupling between the resonant .circuits of a tunable anodestructure cfa high .frequency magnetron rand a tcoupling loop of .an .output circuit.

Magnetron Vconstructions employing a resonant anode structure, including .an .array -of .tuned cir- .cuits arranged .about a central .Opening in which the electrons constituting thespace ,charge of the magnetron are .adapted Ltomove, .havebeen Widely .used'as .asource `of high frequency electric .oscillations. Itis oftendesirable toprovidefmeansffor tuning the .resonant anode ,structure to .determine or control the frequency lat which the ,magnetron In `the copendingNelson .application Serial No. 566,238., ledDecember .2, 1944, entitled Electric .discharge ,devices rand .assigned to the assignee of the present invention, now matured into Patent znzaioojgranted only 2 2., 1947, is

.described and ,claimed a tuning .arrangement for Amagnetrons in which `a pair of diSksarrangedLat in the above-identied Nelsonfapplication, the

range of tuning. efciency and stability I opera tion may be .increased 'by varying the .coupling vbetween the .tuned circuits of 'the anode and 'the output circuit. 'In accordance .with an important feature of our invention, we ,provide means 4:for varying the .coupling Zbe'tween the tuned circuits of the anode and the output `circuitas the' operating frequency is adjusted. j

It is an ,object of our invention to provide .a new and improved magnetron deviceJ It is another object oi our invention to provide a new and .improved .tuning arrangement Afor magnetrons. v v

It is still another volojject of our Vinvention Vto provide new and improved Ahigh frequency .apparatus including a resonant anode structureeand an output `circuit in which .the effective coupling between the ,outputcircuit and the resonant structure is varied .with variations Ain .the .operating frequency. 1 v i i In accordance with the illustrated embodiment of our invention, we provide .a .magnetron including .a vane-type resonant :anode `structure vehicle.

is .tunedby a pair of, .disk-like members ,of diner cnt .diameters located on opposite ,sides of the anode and rigidly secured together sothat they move .in unison Las the magnetron is tuned. One .tuning disk is `arranged Lto control ,predominately the capacitive component .of thetuned circuits andthe other disk, hereinafter sometimes called `L ring, ris .arranged tocontrol predominately the .inductive `component oithetuned circuits. As .the .capacitative tuning element moves closer 'to itheanode structure .and the inductive tuning ele- .ment moves .away'from 'the anode structure, the inductance g and .capacitance Vare .s'imultaneousli7 increased, .thus tuning the anode to a lower operating frequency. accordance with our in- .ventionQ Vwe provide a vane `extending from the edge yof the capacitive tuning element in .alignment with the coupling loop of the. output circuit `to .cutoi a portion of theiiuxwhichwwm otherwise link the .,outputloop. V.This vane reduces the effectine counlinebetween the anode and the out- .put circuit ,as the operating frequency isrlowered,

]sired change' incouplingwith position of the ,L-ring 'is attained L)oy a collarY conforming generally with the Vshape of theloutput loop and extending into the anode cavity A in the direction of u the vloop. fAlso, a land `on the lower side of the L-ring o'f less thickness than the collar vand conforming to the space between adjacent radial vanes is` employed 'to compensate for the `lowered reluctance to magnetic eld caused by the presence of the hole inthe tuning ,disk,

Ofur invention .W'illjbe better understood by 'reference to the viollovwing description .taken in connection with the accompanying drawing, and its scope will .be pointed out in the appended claims. In the drawing, Fig. l is an elevational view, partially section, ci a magnetron device embodying your invention; Fig. `2 is .a sectional view taken along theline 2-2 .of Eig. l, and Fig, 3 'is a sectional view .taken along the line 3-3 of Fig. 41.

Referring now tothe drawing, our invention has rbeen'illustrated as .embodied ina magnetron e5.;

`device including la .generally .cylindrical envelope I, preferably formed of good conducting material such as copper. The cylinder is closed by a cover plate 2 and a bottom plate 3 which may be joined to the side wall of the envelope in any suitable manner. In the particular embodiment illustrated, the resonant anode structure is formed integrally with the sidewall of the envelope and includes a circumferential portion 4 and a plurality of equally spaced radially extending vanes 5 terminating short of the centernof the envelope to define a generally cylindrical space within which the cathode 6 of the` device is positioned.

In one desired mode of oscillation of the resonant anode structure, the `portions of adjacent vanes facing the cathode are displaced 180 electrical degrees. Operation in this m'ode is enhanced by connecting alternate vanes by conducting members at the ends thereof adjacent the central opening ofthe anode structure. As shown in the drawing, annular conducting straps 'I and 8 are secured to the lower face of the anode structure concentrically with the central opening in the anode. These straps 1 and 8 are contuned to higher operating frequencies, opening 2D is formed in inductive tuning disk II4 in alignment with the output loop I8 and of the same general shape. While this opening alone has the eifect of increasing the coupling, operation of the device is improved by providing a depending flange 2| ofthe same general shape as the output loop and surrounding the opening 2U. This flange terminates at about the plane of the loop IB when the tuning disk I I is in its lowest position,

that is when the magnetron is tuned to its highest nected with different sets of alternate anode sections and each strap is insulated from the other set of vanes by recesses 9 which provide suitable clearance between the vanes and the straps. The straps 1 and 8 provide a flat surface which cooperates with the capacitive tuning element to vary effectively the capacity of the various circuits of the anode structure. As illustrated in the drawing, the capacitive tuning member is a disk IIJ, preferably formed of conducting material such as copper. ranged on the opposite side of the anode and connected rigidly with the disk I0 by supporting rods I2 which are adjustably supported from the cover plate 2 by adjusting caps I3. As illustrated in Fig. 1, the cap I3 is threaded on a collar I4 extending upwardly'fromthe cover plate 2, and the supporting rod I2 is rotatably received in the adjusting cap I3. A flexible bellows I5 sealed to the cover plate 12 and to the supporting rod I2 seals the envelope while permitting axial movement of the supporting rod I2. The tuning arrangementjust described is in general similar to that described and claimed in the aboveidentiiied Nelson application.

An output circuit for extracting energy'from the high frequency field produced in the resonant anode structure is provided by a concentric transmission line including an outer conductor I G threaded into the envelope I, and a central conductor I'I terminating in a loop I8 in one of the resonant cavities defined by adjacent vanes ofthe anode structure. It will be understood that the transmission line is hermetically sealed at some point along its length to complete the enclosure for the magnetrondevice.

In order to modify the coupling between the output loop I '8 and the iiux in the resonant anode structure as the tuning members I0 and II are adjusted in position, we provide a flange or paddle-like extension I9 on the edge of the capacitive tuning disk I0 and extending in alignment with the output loop I8. It will be apparent that this paddle functions to choke oiT a portion of the flux which would otherwise link the anode structure and the output loop as the disk I0 is moved closer to the anode structure, in this way decreasing the effective coupling with the output as the device is tuned to lower operating frequencies. In order to increase the flux linking the output loop I8 and the effective coupling with the anode structure as the device is A larger disk II is ar-Y Voperating frequencies.

frequency. An extension or land 22 on the lower face of the tuning disk II, conforming essentially to the space between the vanes bounding the output loop I8 behind the flange 2 I, further improves the operationof the device as itis tuned to higher This land is preferably considerably shallower than the flange 2|. In order to'maintain the` tuning assembly of the same high frequency potential as the envelope, a plurality of iiexible shorting strips 23 are connected between the tuning disks II and the cover plate2. These strips are flexible enough to permit free movement of the tuning assembly and are effective to prevent the introduction of extraneous frequencies into theV system.

The cathode 6 is supported from the cover plate 2 by a hollow supporting tube 24 which is secured to a sleeve 25 by a cap 25'. The sleeve '25 is sealed to the upper end of an insulating sleeve 26, preferably of glass and having its lower end sealed to the upperend of an upstanding sleeve 2l formed on the cover plate 2. The upper end 28 of the tube 24 provides the cathode terminal which may also provide the external connection for one side of the heater element (not shown). The other heater element is positioned centrally of the supporting, tube 24 and maintained in insulated relation with respect thereto by a suitable spacing insulator 30. The conductor 29 extends from the upper end of ,the tube 24 and is sealed thereto by a body of glass 3|.

g A magnetic field is produced in the space between the cathode 6 andthe endsof the vanes 5 by suitable permanent or electromagnetic means (not shown) having pole pieces 32 and 33 located opposite Y,the ends of the cathode 6 and on the exteriorof the envelope.

The operation of the embodiment of my inven- .tion described above as a source of high frequency electrical oscillations is believed to be generally understood. Briefly, this operation is as follows:

`Electrons emitted from the surface of the cathode 6 move in the annular space between the cathode and the ends of the radial vanes 5 in curvilinear paths determined by the geometry of the anode structure `and the resultant action of mutually perpendicular electric and magnetic fields produced, respectively, by a voltage across the anode and. cathode and by the pole pieces 32 and 33. Movement of the electrons excites the anode structure and causes electrical oscillations at a frequency determined by the constants of the mutually coupled circuits formed by the radial vanes. Energy is extracted from the high frequency field produced in the openings'through the anode by means of the output loop I8 which is connected with the central conductor of the output transmission line. As the tuning structure is moved downwardly, as viewed in Fig. 1, plate II, which is the inductive tuning element, moves closer to the anode structure choking off a portion of the high frequency flux which normally passes throughl the openings of the anode and the capacitive tuning element I0 is moved away from the Ainductive lcompor'lrlts of reactance "'off the tuned vided to control the ychange in couplingv with operating frequencyin such'a'manner as to maintain efiiciency and stability over a wide range of operf' ation. The paddle or vane extension i9 on the capacitive tuning j elementjl 0'- functions to decrease the coupling'between the flux of the anode structure and the output loop Vas the device is tuned to a lower operating Ifrequency, with the result that the stability "of, the loscillations is increased.

While we haveshown and described a particular embodiment of our invention, it will be obvious to those skilled in the vart that'changes and modifications may be made'without 'departing from our invention in Vits broader aspects, and we, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true 'spirit andA scope of our invention;

What we Yclaim as new and' desire tosecure by Letters Patent of the AUnited States is:

1. An electric discharge device comprising a space resonant structure adapted to be excited into high frequency oscillation by the space charge of said device, means adjacent said structure for tuning said structure to different operating frequencies, an output element coupled to said structure, and means intercoupling said means and said output element for varying the coupling between said resonant structure and said output element as the operating frequency is varied.

2. An electric discharge device comprising a space resonant structure adapted to be excited into high frequency oscillation by the space charge of said device, means adjacent said structure for tuning said structure to different operating frequencies, an output means including a loop conductor coupled to said structure, and means intercoupling said means and said output means for increasing the coupling between said resonant structure and said output means as the operating frequency is increased.

3. An electric discharge device -comprising an anode structure including an array of cavity resonators about a central opening within which the electrons constituting the space charge of the device are adapted to move, a tuning stru-cture mounted adjacent said anode structure for movement with respect to said anode structure for controlling the operating frequency of said device, an output loop positioned in one of said cavity resonators, and means intercoupling said tuning structure and said loop for varying the coupling between the high frequency flux of said anode structure and said output loop as said tuning Y structure is moved with respect to said anode.

4. An electric discharge device comprising an anode structure including an array of cavity resonators about a central opening within which the electrons constituting the space charge of the device are adapted to move, a tuning structure Y mounted adjacent said anode structure for movement with respect to said anode structure for controlling the operating frequency'of said device, an output element coupled to said anode' structure, and meansintercoupling said tuning structure and said output elementfor varying the coupling between the high frequency flux of' said anode structure and said output element as said tuning-structure is moved withres'pect to said anode. Y Y 1 5. An electric discharge device of the magnetron type including an anode having a plurality 0f openings forming a'pluralit'y of coupled cavity resonators, a source of electronsV adjacent said anode for exciting said-anode into high frequency oscillation, a tuning member adjacent said anode movable with respect to said anode for controlling the operating frequency of said device, an output element coupled to said device including a loop conductor coupled to one of said cavity resonators for coupling with the flux'thereo'f, said tuning member having a recessed portion adjacent to said loop conductor to increase the coupling Vbetween said anode and said output'ele- -ment as said device is tuned to higher operating frequencies. n i i `6. An electric discharge device including' an anode having a plurality of openings forming a plurality of coupled cavity resonators, a source lof electrons adjacent said anode for exciting said anode structure into high frequency oscillation, a tuning member mounted adjacent said anode and movable with respect to said anode for controlling the operating frequency of said device and overlying a portion of ,'each'of said openings, an output means including a loop conductor coupled Y to one of said cavity resonators for coupling with the flux of one of the openings of said anode, said tuning member having an opening in alignment with said loop to maintain the coupling between said anode and said output means as said device is tuned to higher operating frequencies.

'7. An electric discharge device including an anode having a plurality of openings forming a plurality of coupled cavity resonators, a source of electrons adjacent said anode for exciting said anode structure into high frequency oscillation, a tuning member mounted adjacent said anode and movable with respect to said anode for controlling the operating frequency of said device and overlying a portion of each of said openings, an output means including a loop conductor coupled to one of said cavity resonators for coupling with the iiux of one of the openings of said anode, said tuning member having an opening in alignment with said loop and a curved liange extending from said member into said one of said openings and about said loop to control the flux linking said loop and said anode as said tuning member is moved toward and away from said anode.

8. An electric discharge device of the magnetron type, comprising an anode structure having a plurality of openings therein forming a plurality of coupled cavity resonators, rst and second tuning members mounted on opposite sides of said anode and movable with respect thereto for changing the operating frequency of said device, an output element coupled to said device, means supported from said rst mentioned tuning member for decreasing the coupling with said output element as said member is moved toward said anode structure, said second tuning member having an opening therein juxtaposed to said output element for increasing the coupling with said output element as said second tuning member is moved towards saidranode structure.

9. An electric discharge device of the magnetron type, comprising an anode structure having a plurality of openings therein forming a plurality of coupled cavity resonators, first and second tuning members mounted on opposite sides of said anode and movable with respect thereto for changing the operating frequency of said device, an output means coupled to said device including a coupling loop, a ilange supported from said iirst mentioned tuning member and in alignment with said loop for decreasing tne coupling with said output means als said member is moved toward said anode structure, said second tuning member having an opening juxtaposed to said loop in alignment with said loop for increasing the coupling with said output means as said second tuning member is moved towards said anode structure. Y y

10. An electric discharge device comprising an anode structure having a plurality of vspaced openings the walls of which deiine` an array of cavity resonators about a central opening within which the electrons constituting the space charge of the device are adapted to move, a tuning member mounted adjacent said anode structure for movement withV respect to said anode structure for controlling the operating frequency of said device and extending over said openings, an output means including a loop positioned in one of said openings, said member having an opening in alignment with said loop, and means extending from said member into the opening in said anode 'structurein which saidloop is located and conforming generallyto theportion of said last mentioned opening notoccupied by said loop.

11. An electric discharge device of the magnetron type including an anode having a vplurality of openings forming a plurality of coupled cavity resonators, a` source of electrons adjacent said anode for exciting said anode into high frequency oscillation, an output means comprising a loop conductor coupled to one of said cavity resonators for coupling with the flux thereof, a tuning member adjacent said anode and moveable with respect theretofor controlling the operating frequency of said device, said tuning member including a portion juxtaposed to said loop, the edge of said portion having an open shape in the Vicinity of said loop whereby coupling between said anodes and said output means is increased as said tuning member approaches said anode.

ROBERT N. HALL. AMANDUS H. SHARBAUGH. LEWI TONKS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STA'I'ES PATENTS Number Name Date 2,163,589 Dallenbach et al. June 27, 1939 2,167,201 Dallenbach July 25,1939 2,348,986 Linder May 16, 1944 2,424,496 Nelson July 22, 1947 

